ld: fix implementation of -u

R=r
CC=golang-dev
https://golang.org/cl/1678046

src/cmd/ld/go.c

@@ -75,7 +75,7 @@ static int ndynexp;
 static Sym **dynexp;
 
 void
-ldpkg(Biobuf *f, char *pkg, int64 len, char *filename)
+ldpkg(Biobuf *f, char *pkg, int64 len, char *filename, int whence)
 {
 	char *data, *p0, *p1, *name;
 
@@ -100,7 +100,7 @@ ldpkg(Biobuf *f, char *pkg, int64 len, char *filename)
 	// first \n$$ marks beginning of exports - skip rest of line
 	p0 = strstr(data, "\n$$");
 	if(p0 == nil) {
-		if(debug['u']) {
+		if(debug['u'] && whence != ArchiveObj) {
 			fprint(2, "%s: cannot find export data in %s\n", argv0, filename);
 			errorexit();
 		}
@@ -133,20 +133,31 @@ ldpkg(Biobuf *f, char *pkg, int64 len, char *filename)
 		name = p0;
 		while(p0 < p1 && *p0 != ' ' && *p0 != '\t' && *p0 != '\n')
 			p0++;
-		if(debug['u'] && memcmp(p0, " safe\n", 6) != 0) {
+		if(debug['u'] && whence != ArchiveObj &&
+		   (p0+6 > p1 || memcmp(p0, " safe\n", 6) != 0)) {
 			fprint(2, "%s: load of unsafe package %s\n", argv0, filename);
 			errorexit();
 		}
 		if(p0 < p1) {
+			if(*p0 == '\n')
 				*p0++ = '\0';
+			else {
+				*p0++ = '\0';
+				while(p0 < p1 && *p0++ != '\n')
+					;
+			}
+		}
 		if(strcmp(pkg, "main") == 0 && strcmp(name, "main") != 0)
 			fprint(2, "%s: %s: not package main (package %s)\n", argv0, filename, name);
 		else if(strcmp(pkg, "main") != 0 && strcmp(name, "main") == 0)
 			fprint(2, "%s: %s: importing %s, found package main", argv0, filename, pkg);
-		}
 		loadpkgdata(filename, pkg, p0, p1 - p0);
 	}
 
+	// The __.PKGDEF archive summary has no local types.
+	if(whence == Pkgdef)
+		return;
+
 	// local types begin where exports end.
 	// skip rest of line after $$ we found above
 	p0 = p1 + 3;

src/cmd/ld/lib.c

@@ -35,6 +35,7 @@
 int iconv(Fmt*);
 
 char	symname[]	= SYMDEF;
+char	pkgname[]	= "__.PKGDEF";
 char*	libdir[16];
 int	nlibdir = 0;
 int	cout = -1;
@@ -286,7 +287,7 @@ objfile(char *file, char *pkg)
 		/* load it as a regular file */
 		l = Bseek(f, 0L, 2);
 		Bseek(f, 0L, 0);
-		ldobj(f, pkg, l, file);
+		ldobj(f, pkg, l, file, FileObj);
 		Bterm(f);
 		return;
 	}
@@ -304,6 +305,25 @@ objfile(char *file, char *pkg)
 	esym = SARMAG + SAR_HDR + atolwhex(arhdr.size);
 	off = SARMAG + SAR_HDR;
 
+	if(debug['u']) {
+		struct ar_hdr pkghdr;
+		int n;
+
+		// Read next ar header to check for package safe bit.
+		Bseek(f, esym+(esym&1), 0);
+		l = Bread(f, &pkghdr, SAR_HDR);
+		if(l != SAR_HDR) {
+			diag("%s: short read on second archive header", file);
+			goto out;
+		}
+		if(strncmp(pkghdr.name, pkgname, strlen(pkgname))) {
+			diag("%s: second entry not package header", file);
+			goto out;
+		}
+		n = atolwhex(pkghdr.size);
+		ldpkg(f, pkg, n, file, Pkgdef);
+	}
+
 	/*
 	 * just bang the whole symbol file into memory
 	 */
@@ -350,7 +370,7 @@ objfile(char *file, char *pkg)
 				l--;
 			sprint(pname, "%s(%.*s)", file, l, arhdr.name);
 			l = atolwhex(arhdr.size);
-			ldobj(f, pkg, l, pname);
+			ldobj(f, pkg, l, pname, ArchiveObj);
 			if(s->type == SXREF) {
 				diag("%s: failed to load: %s", file, s->name);
 				errorexit();
@@ -368,7 +388,7 @@ out:
 }
 
 void
-ldobj(Biobuf *f, char *pkg, int64 len, char *pn)
+ldobj(Biobuf *f, char *pkg, int64 len, char *pn, int whence)
 {
 	static int files;
 	static char **filen;
@@ -433,7 +453,7 @@ ldobj(Biobuf *f, char *pkg, int64 len, char *pn)
 	import1 = Boffset(f);
 
 	Bseek(f, import0, 0);
-	ldpkg(f, pkg, import1 - import0 - 2, pn);	// -2 for !\n
+	ldpkg(f, pkg, import1 - import0 - 2, pn, whence);	// -2 for !\n
 	Bseek(f, import1, 0);
 
 	ldobj1(f, pkg, eof - Boffset(f), pn);

src/cmd/ld/lib.h

@@ -88,8 +88,8 @@ void	libinit(void);
 void	Lflag(char *arg);
 void	usage(void);
 void	ldobj1(Biobuf *f, char*, int64 len, char *pn);
-void	ldobj(Biobuf*, char*, int64, char*);
+void	ldobj(Biobuf*, char*, int64, char*, int);
-void	ldpkg(Biobuf*, char*, int64, char*);
+void	ldpkg(Biobuf*, char*, int64, char*, int);
 void	mark(Sym *s);
 char*	expandpkg(char*, char*);
 void	deadcode(void);
@@ -102,3 +102,10 @@ void	mywhatsys(void);
 extern	char*	goroot;
 extern	char*	goarch;
 extern	char*	goos;
+
+/* whence for ldpkg */
+enum {
+	FileObj = 0,
+	ArchiveObj,
+	Pkgdef
+};